Figure 1. Construction and characterization of the polyelectrolyte multilayer films. (A) Diagram of development and structure of a multilayer film based on the alternate deposition of polyanions (grey) and polycations (black). (B) Build-up of a Pre-(PGA-PLL)₉ multilayer film, followed by quartz crystal microbalance (QCM) assessment. Global increase in the adsorbed mass is shown by the exponential increase in frequency shift (f at 15 Hz, = 3). The exponential regression follows the function: y = y0 + Aexp(Bx) (with y0 = –398.7, A = 431.8, B = 0.1, R = 0.999). (C) Vertical section obtained by confocal laser scanning microscopy (CLSM) observation through a Pre-(PGA-PLL)₂₀-PGA-PLL^FITC film on a glass substrate. The film thickness is about 1 µm.